The glycolytic pathway in the human parasite, Entamoeba histolytica, presents a striking deviation from the usual Embden- Meyerhof pathway between glucose and pyruvate. The last enzyme of the sequence, pyruvate kinase, is lacking in the parasite. In its stead is found an enzyme called pyruvate phosphate dikinase which converts P- enolpyruvate (PEP) to pyruvate as follows: PEP plus AMP plus PP sub i yeild pyruvate plus ATP plus P sub i. Inorganic pyrophosphate (PP sub i) for the above reaction is apparently supplied by a second enzyme acting also on PEP. It is PEP carboxy-transphosphorylase, catalyzing the following reaction: PEP plus CO2 plus P sub i Oxaloacetate plus PP sub i. Molecules of PEP which are converted to oxaloacetate may be transformed further to pyruvate. It is now proposed to show if the abundant amebal enzymes which catalyze steps I-IV individually may function as a system in the postulated direction in the living cell. Amebae will be tested to learn if they are capable on gluconeogenesis. The four enzymes will be individually purified and their properties studied. Reaction kinetics will reveal if the four enzymes are capable of forming a compatible system for conversion of PEP to pyruvate at the rate demanded. In living cells a steady state PP sub i pool should be reached and p32 from orthophosphate should rapidly be incorporated into this pool. Label from glucose should appear simultaneously in pyruvate, oxaloacetate, and malate, while label from CO2 should appear, initally, only in the last two. Finally, the mechanism of action of the dikinase and transphosphorylase enzymes will be studied.